JP2002237377A - Induction heating method, device fixing device, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device which reduces idle current given to a commercial alternating current, enabled to output a constant heating output at low cost, with high fixing property, and to provide an image forming device with high fixing property, without lowering of image quality. SOLUTION: The fixing device comprises a conductive roller 1, a temperature sensor 20, an induction heating coil 2 and a resonance capacitor 10, a rectifying circuit 19 supplying power to the coil 2, a switch 17 and a flywheel diode 28 of which output direct current is chopped and conducted to the coil 2, a voltage detecting circuit 14 detecting the voltage at the contact point of the coil 2 and the switch 17, current detecting circuits 29, 18 detecting the current of the switch 17 and a control means switching on the switch 17 by synchronizing with the resonant vibration of the voltage at a contact point, and switching off when an added value, got by biasing the detected current signal of the switch 17 to the extent of temperature deviation, gets to the instantaneous value of envelope level of switching current. The quality of the roller material is determined from the switching current, and regeneration current of the diode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to induction heating in which an alternating current is applied to an electric coil (induction heating coil) to generate an induction current in a conductor immediately adjacent to the induction coil. PWM to supply power by chopping with an inverter to a resonance circuit including an induction heating coil and a resonance capacitor connected to the induction heating coil.
It relates to induction heating control. For example, a heat treatment or heat treatment apparatus such as a metal melting furnace, a steel induction heating furnace, a plate material heating furnace, a quenching furnace, a fixing apparatus used in an image forming process, and an image of a printer using a fixing apparatus, a facsimile machine, and a copying machine. Applies to forming equipment.

[0002]

2. Description of the Related Art For example, in an electrophotographic printer, a facsimile, and a copying machine, a fixing device is provided inside a fixing device for fixing a developed image to an image forming material such as a recording sheet or paper. The main part of this fixing device is composed of a fixing roller for heating the sheet to which the unfixed toner has adhered, and a pressure roller for pressing the sheet and for nipping and conveying.

Conventionally, such a fixing device includes a halogen lamp or the like as a heater inside the fixing roller, heats the inside of the fixing roller with the lamp, and heats the fixing roller to a predetermined target temperature suitable for fixing required by toner. Was going to rise.

However, such a heating method using a halogen heater takes a long time until the fixing roller is heated to a required temperature, and the loss of the heater itself is large, so that environmental problems such as global warming are present. Therefore, there is a need for a fixing device that is efficient and has a fast rise time.

In such a situation, it has been proposed to use an "induction type heating roller" as a heating roller for a toner fixing device of a printer. For example, JP-A-53-508
44, JP-A-6-60975 and JP-A-20
There are several disclosures in 00-330404. In a fixing device using this roller, that is, a fixing device using an induction heating method, the fixing roller can be instantaneously heated by an eddy current caused by an electromagnetic wave, so that the time required for heating can be significantly reduced.

[0006] For this reason, even in the standby mode when the printer is not used, such as required in the conventional halogen lamp system, the temperature of the fixing unit is increased so that the temperature of the fixing unit quickly rises to a predetermined temperature when reused. Since it eliminates the need for unnecessary power and eliminates the need for unnecessary power and has a good heating efficiency, it is attracting attention as a method that can contribute to environmental problems.

Although the induction heating type fixing device has such advantages, when an actual device is constructed, the configuration of an inverter circuit for applying a high frequency to the coil is important. Depending on the situation, it is desirable to solve various problems, such as improvement of the power factor due to high frequency, noise problem, countermeasures against the fixing roller of the imitation product, and response to cost reduction to further increase product value.

FIG. 15 is a block diagram of a conventional induction heating apparatus. When the induction heating type device is implemented as a fixing device, a metal fixing roller or a metal plate,
An induction heating coil 2 for generating an induction current in the object 1 to be heated is disposed near the object 1 to be heated. The induction heating coil 2 has a commercial power supply (AC10).
0V) The AC of 7 is rectified into DC by the rectifier circuit 19, converted into a high frequency by an inverter circuit below the resonance capacitor 10 and applied (by high frequency chopping). A thermostat 4p, which is a safety protection component, is provided on or near the surface of the object 1 to be heated, and a current to the inverter circuit is supplied via the thermostat 4p. When the power supply current becomes negative, the power supply current is cut off by the thermostat 4p.

The rectifier circuit 19 rectifies AC100V into DC, and forms an induction heating coil 2 constituting an LC resonance circuit.
Is applied to the resonance capacitor 10. Rectifier circuit 19
Comprises a bridge diode 8 for full-wave rectification and a smoothing capacitor 9. When the capacity of the smoothing capacitor 9 is large, the voltage output from the rectifier circuit 19 and applied to the LC resonance circuit including the coil 2 and the resonance capacitor 10 has a level variation width as shown in FIG. When the capacity of the smoothing capacitor 9 is extremely small, the waveform becomes a full-wave rectified waveform having a large level fluctuation width and a high similarity with the AC voltage as shown in FIG.

The rectifier circuit 19 and the LC resonance circuit (2
+10), which is supplied by switching a switching element, for example, a transistor, an FET, an IGBT, or the like, that is, a switch 17, which is connected in series with the driving circuit 15. The ON timing of the switch 17 is determined by the voltage detection circuit 14, and the OFF timing is determined by the control circuit 16 and the current detection circuit 18. That is, the control circuit 16 designates the reference off timing (on time) to the drive circuit 15, and the current detection circuit 18 uses the constant voltage supplied from the circuit DC power supply 11, which is a constant voltage power supply, to generate the reference voltage 20. An error voltage indicating a deviation of a current signal (a voltage proportional to the detected current value) generated by the current detection circuit 18 from a generated reference voltage (a constant value) is given to the driving circuit 15.
In the direction in which this error voltage decreases, the off timing
It is shifted from the reference off timing specified by the control circuit 16.

When the switch 17 is repeatedly turned on and off, a high-frequency current flows through the coil 2 to perform induction heating of the object 1 to be heated. That is, the high frequency (switching frequency) applied to the coil 2 by this switching operation is automatically determined to be the resonance frequency of the resonance circuit (2 + 10).

When the control system of this conventional example is used, for example, when the output voltage of the rectifier circuit 19 is extremely weak and has a large pulsation as shown in FIG. In the full-wave rectified waveform, as shown in FIG. 16 in which a peak of one wave is enlarged, the off-timing is controlled so that the current detection level always becomes a value corresponding to the reference voltage, so that the voltage applied to the coil 2 is high. At times, the switch-on time becomes short and the frequency becomes high, and when the voltage applied to the coil 2 is low, the switch-on time becomes long and the frequency becomes low, and when the frequency falls below the audible band of 20 kHz, the noise becomes low. Becomes

Rectifier circuit 1 for supplying DC power to inverter circuit
9, the capacity of the smoothing capacitor 9 is increased to reduce the level fluctuation range of the DC pulsation as shown in FIG. 2A, and this voltage is formed by the combination of the induction heating coil 2 and the resonance capacitor 10. By applying the voltage to the resonance circuit, the fluctuation of the voltage applied to the coil is small, so that the fluctuation of the on-duty of the switching (the ratio of the on-time to one on / off cycle) (for example, FIG. 16) becomes extremely small, which may cause noise. Disappears.

[0014]

However, the smoothing capacitor of the rectifier circuit 19 for supplying DC power to the inverter circuit.
If the capacity of 9 is large, the phase of the commercial power supply voltage and the consumption current will be shifted, and a reactive current will be generated. Therefore, it is necessary to take measures for regulating the harmonic current, which leads to an increase in the cost of the device. In addition, the use of a large-capacity smoothing capacitor is not preferable because of the problems of an increase in the cost of the device and an increase in the size of the device itself. further,
In the conventional halogen lamp system, there is a problem that the imitation product fixing roller circulates, and in some cases, the image quality may be deteriorated.

Accordingly, it is an object of the present invention to reduce reactive current, to avoid generation of audible frequency noise, and to keep heating output constant with an inexpensive configuration. Another object of the present invention is to provide a fixing device that meets these requirements and has a high fixing performance. Another object of the present invention is to provide an image forming apparatus that has a high fixing performance and does not cause deterioration in image quality. Aim.

[0016]

Means for Solving the Problems (1) A switching element is provided in a resonance circuit including an electric coil (2) disposed in the immediate vicinity of a heating target (1) and a resonance capacitor (10) connected thereto.
In the induction heating method in which the alternating current is rectified and the direct current is chopped by repeating the on / off operation of (17), the fluctuation of the voltage between the resonance circuit and the switching element is detected, and the switching element is turned on in synchronization therewith. And
Detecting a current flowing through the switching element, and turning off the switching element after an on-time based on a time until the instantaneous value of an envelope level proportional to the voltage waveform obtained by rectifying the AC is reached. An induction heating method characterized in that:

In order to facilitate understanding, the symbols of the corresponding elements or corresponding items in the embodiments shown in the drawings and described later are added for reference in parentheses. The same applies to the following.

At the timing when a low-level voltage of a voltage waveform obtained by rectifying an alternating current is applied to the switching element, the instantaneous value of the current value is low because the voltage is low conventionally, and the on-time is long. According to this, at that time, the instantaneous value of the envelope level proportional to the voltage waveform obtained by rectifying the alternating current is low, so that the on-time is shorter than in the conventional case, that is, the on-duty of the switching element does not increase as in the conventional case.

At the timing when a high-level voltage of a voltage waveform obtained by rectifying an alternating current is applied to the switching element, the instantaneous value of the current value is high because the voltage is conventionally high and the on-time is short. According to this, at that time, the instantaneous value of the envelope level is high, so that the on-time is longer than before, that is, the on-duty of the switching element does not become lower than before.

That is, even when the voltage waveform obtained by rectifying the alternating current has a large level variation substantially similar to, for example, the positive half-wave of the input alternating current (for example, FIG.
The duty of the M conduction does not fluctuate particularly. It is constant or almost constant. As a result, the peak value of the current flowing through the switching element during one PWM cycle is a value shown by a sharp sawtooth wave (one wave is one ON period) in FIG. 3, and the time series distribution of the peak value is AC. Draw a similar envelope to the rectified voltage waveform. The instantaneous value of this envelope is used to determine the off timing of the switching element. Alternatively, an output of a rectifier circuit applied to the resonance circuit, that is, a voltage waveform obtained by rectifying an alternating current may be detected or generated and used as the envelope level.

In any case, the voltage waveform applied to the resonance circuit is similar to the envelope drawn in time series with the peak value during one PWM cycle of the current flowing through the switching element,
The current (peak value) flowing through the switching element is proportional to the voltage (instantaneous value) of the voltage waveform, and the ON time during one PWM cycle is substantially constant. In other words, the on / off on-duty of the switching element by PWM becomes substantially constant.

Since the duty of the PWM conduction of the switching element is constant or substantially constant, the smoothing capacitor of the circuit for rectifying the AC does not have a large capacity, that is, the voltage waveform obtained by rectifying the AC is equal to the positive half wave of the input AC. No significant frequency drop occurs even when the substantially similar level fluctuations are large or when the voltage is low. For example, dropping to an audible frequency of 20 KHz or less can be avoided.

(2) The induction heating method according to the above (1), wherein the temperature of the object to be heated (1) is detected and the on-time is adjusted so as to match a target value. The temperature of the object to be heated can be controlled to a target value by adding, for example, an increase or decrease corresponding to the deviation of the detected temperature from the target temperature to the on-time obtained in the above (1).

(3) When a diode (28) is connected in anti-parallel to the switching element (17), a regenerative current flowing through the diode is detected, and a regenerative current between the switching element and the regenerative current is detected. The induction heating method according to the above (1), wherein based on the combination, at least one of the presence of the heating target (1) near the electric coil (2) and the material of the heating target (1) is detected.

As shown in FIG. 10, the value of the regenerative current depends on the material of the object to be heated (1) and the value of the load current flowing through the switching element. Less power to do. Therefore, the regenerative current value is large. This means that induction heating is disadvantageous. When the heating target is iron, contrary to aluminum, the power consumption of the heating target is large, the regenerative current value is low, and it means that induction heating is advantageous. If the object to be heated is stainless steel, the power consumption characteristic of induction heating is between aluminum and iron. When there is no object to be heated near the induction coil (2) and there is no load, there is no power consumption, and an excessive regenerative current flows.

Focusing on the difference in the magnitude of the regenerative current flowing through the diode with respect to the load current value flowing through the switching element due to no load or the material to be heated, the presence or absence of the material to be heated and the material to be heated are determined. Can be determined.
In the embodiment (3), for example, the regenerative current value (Sk) is read while sequentially increasing the on-duty of the switching element, and the switch current value (Sin) when the regenerative current value (Sk) reaches a predetermined value, for example, 20A. ) Is a predetermined value, for example, 3
If the current is 0 A or more, the material is determined to be iron. Otherwise, if the switch current value (Sin) exceeds 10 A, the material is determined to be stainless steel. Otherwise, the switch current value (Sin) is further increased and the regenerative current is increased. When the value exceeds 80 A, if the switch current value (Sin) exceeds 3 A, the material is determined to be aluminum, otherwise, it is determined that there is no load (no roller).

For example, if the regenerative current value exceeds 40 A before the current value of the switching element becomes 2 A, it is determined that there is no load (there is no object to be heated). Regenerative current value is 60A
Is exceeded, the object to be heated is determined to be aluminum or an unsuitable material for induction heating.
If the regenerative current value exceeds 10 A before exceeding A, the object to be heated is determined to be stainless steel or a corresponding induction heatable material.
If it exceeds 0 A, the object to be heated can be determined to be iron or a material suitable for induction heating corresponding thereto.

(4) The induction heating method according to the above (3), wherein the on-time is adjusted according to the material to be heated. The above (3)
As described above, even when a current having the same value is applied to the switching element, the regenerative current value differs depending on the material to be heated, so that the power consumption (absorption) speed of the heating object differs. That is, the rate of temperature rise is different, and the temperature rise is slow in aluminum and fast in iron.
Therefore, in this embodiment (4), a material (for example, stainless steel) having inferior induction heating characteristics at a speed equivalent to a reference temperature rising speed determined for a reference material (for example, iron) having good induction heating characteristics.
The current value of the switching element (PWM on-duty) is set high in the case of a material having a poor induction heating characteristic so that the temperature also rises.

(5) An electric coil disposed in close proximity to the object to be heated (1) to generate an induced current therein and generate heat.
(2) and a resonance circuit (2, 10) including a capacitor (10) connected thereto; a rectifier circuit (19) for rectifying AC to DC for supplying power to the resonance circuit; Switching element for energizing chopping in the resonance circuit
(17) and an inverter circuit (26) including a diode (28) connected in anti-parallel thereto;
Drive means (15) for turning off; voltage detection means (14) for detecting a voltage at a connection point between the electric coil (2) and the switching element (17); means (18) for detecting a current flowing through the switching element And an envelope level in which the switching element is turned on via the driving means in synchronization with the resonance oscillation of the voltage detected by the voltage detection means, and the current flowing through the switching element is proportional to the voltage waveform obtained by rectifying the AC. Control means for turning off the switching element after an on-time based on the time until the instantaneous value is reached.

According to this, when the voltage waveform applied to the resonance circuit and obtained by rectifying the alternating current is substantially similar to, for example, the positive half-wave of the input alternating current, and has large fluctuations in height (for example, FIG. 2B).
However, the PWM energization duty of the switching element does not fluctuate particularly. It is constant or almost constant. As a result, the peak value of the current flowing through the switching element during one PWM cycle is a sharp sawtooth wave (one wave is one ON period) in FIG.
, And the time series distribution of the peak values draws an envelope similar to the voltage waveform obtained by rectifying the alternating current. The instantaneous value of this envelope is used to determine the off timing of the switching element. Alternatively, an output of a rectifier circuit applied to the resonance circuit, that is, a voltage waveform obtained by rectifying an alternating current may be detected or generated and used as the envelope level.

In any case, the voltage waveform applied to the resonance circuit and the envelope drawn in time series with the peak value during one PWM cycle of the current flowing through the switching element are similar,
The current (peak value) flowing through the switching element is proportional to the voltage (instantaneous value) of the voltage waveform, and the ON time during one PWM cycle is substantially constant. In other words, the on / off on-duty of the switching element by PWM becomes substantially constant.

Since the duty of the PWM conduction of the switching element is constant or substantially constant, the smoothing capacitor of the circuit for rectifying the AC does not have a large capacity, that is, the voltage waveform obtained by rectifying the AC is equal to the positive half wave of the input AC. No significant frequency drop occurs even when the substantially similar level fluctuations are large or when the voltage is low. For example, dropping to an audible frequency of 20 KHz or less can be avoided.

(6) A cylindrical conductive roller (1) for heating and pressing the recording medium (PR) on which the toner image has adhered;
Means for detecting the temperature of the conductive roller (20); an electric coil (2) arranged close to the conductive roller to generate an induced current therein to generate heat and a capacitor (10) connected thereto A rectifying circuit (19) for supplying AC power to the resonant circuit and rectifying AC to DC; a switching element (10) for supplying an output DC of the rectifier circuit to the resonant circuit by chopping ( 17) and an inverter circuit (26) including a diode (28) connected in anti-parallel thereto; driving means (15) for turning on / off the switching element; the electric coil (2) and the switching element (17). Voltage detecting means (14) for detecting a voltage at a connection point with the voltage detecting means (14); means (29) for detecting a current flowing through the switching element; and the driving means in synchronization with resonance oscillation of the voltage detected by the voltage detecting means. The switching element is turned off through The target temperature of the temperature detected by the temperature detecting means during the on-time based on the time until the current flowing through the switching element reaches the instantaneous value of the envelope level proportional to the voltage waveform obtained by rectifying the AC. Control means for turning off the switching element after a time period in which a correction corresponding to a deviation from the correction value is applied.

According to this, in addition to the operation and effect described in (5) above, the operation and effect that the temperature of the conductive roller (1) is automatically controlled to the target value and is maintained at a constant temperature. Is obtained.

(7) Photoconductor (414) and means for charging the photoconductor
(419), exposure means (441-446) for irradiating the charged surface of the photoreceptor with light for representing an image, developing means (420) for developing an electrostatic latent image formed by toner with toner, Means (415-416) for transferring the imaged toner image directly or indirectly to the recording medium via an intermediate transfer medium, and a fixing device according to the above (6), wherein the recording medium is heated and pressed. 42
3) An image forming apparatus comprising:

According to this, the temperature of the conductive roller (1) of the fixing device (423) is automatically controlled to a target value and is maintained at a constant temperature, so that image recording with stable fixing quality can be obtained. .

(8) A fixing device (423) for fixing the toner image formed on the recording medium (PR) to the recording medium,
An object to be heated (1) formed of a conductive member, a coil (2) disposed close to the object to be heated and generating heat by generating an induced current in the object to be heated; A DC power supply circuit (19) composed of a rectifier circuit (8) and a smoothing capacitor (9) for passing an alternating current through the coil (2) and a capacitor.
(10), an inverter circuit (26) including a switching element (17) and a diode (28) connected in anti-parallel thereto, the coil (2) and the switching element ( 17) Voltage detection means for detecting the voltage at the connection point with
(14), current detection means (29, 18) for detecting a current flowing through the switching element (17), a smooth detection level adjusting means (12) for adjusting the detected current to a smooth detection level, Control means (1) for controlling the drive of the switching element (17) based on a voltage value, a smoothing detection level, and a current value.
6) An induction heating type fixing device characterized by having:

According to this, in the induction heating type fixing device, whether the voltage at the connection point between the coil (2) and the switching element (17) has reached almost 0 V, and whether the voltage applied to the coil (2) is Since the switching of the inverter circuit that generates a high frequency depending on whether the detected current value has reached a smoothed detection level obtained by smoothing the current proportional to the voltage waveform in a similar manner to the voltage waveform is performed, the voltage applied to the coil (2) is The on / off frequency of the switching element (17) becomes constant irrespective of the level of the applied voltage even if it fluctuates as shown in FIG. Also, for example, FIG.
The voltage shown in (b) is when the capacity of the smoothing capacitor (9) is extremely small, and no reactive current is generated, so that it is possible to comply with the harmonic current regulation and to detect the coil current. Since the switching is performed, the heating output can be kept constant, so that the temperature of the object to be heated can be accurately controlled.

(9) A fixing device (423) for fixing the toner image formed on the recording medium (PR) to the recording medium,
An object to be heated (1) formed of a conductive member, a coil (2) disposed close to the object to be heated and generating heat by generating an induced current in the object to be heated; A DC power supply circuit (19) composed of a rectifier circuit (8) and a smoothing capacitor (9) for passing an alternating current through the coil (2) and a capacitor.
(10), an inverter circuit (26) including a switching element (17) and a diode (28) connected in anti-parallel thereto, the coil (2) and the switching element ( 17) Voltage detection means for detecting the voltage at the connection point with
(14) current detecting means (30, 31) for detecting the current value of the current flowing through the diode (28); smoothing detection level adjusting means for adjusting the detected current to a smooth detection level; Control means for driving and controlling the switching element based on the detected voltage value, the smoothed detection level and the detected current value (16)
And an induction heating type fixing device comprising:

According to this, in addition to the function and effect of the above (8), by controlling the driving of the switching element based on the regenerated current value (current flowing through the diode), the switching element is smaller than the coil current. Since the current value is detected, the loss of the detection unit can be reduced.

(10) A fixing device (423) for fixing a toner image formed on a recording medium (PR) to the recording medium, comprising: a heated member (1) formed of a conductive member; A coil (2) disposed close to the object to be heated, for generating an induced current in the object to be heated to generate heat, and a rectifier circuit (8) and a smoothing capacitor for flowing an alternating current through the coil. (9)
A DC power supply circuit (19), a resonance circuit (2, 10) including the coil (2) and a capacitor (10), and a switching element (1).
7) and an inverter circuit (26) composed of a diode (28) connected in anti-parallel thereto, and a voltage detecting means (14) for detecting a voltage at a connection point between the coil (2) and the switching element (17). ), A current detection means 1 (18) for detecting a current flowing through the switching element (17), and a smooth detection level adjustment means 1 (12) for adjusting the detected current to a smooth detection level 1.
Current detecting means 2 (30, 31) for detecting a current value of a current flowing through the diode (28); smoothing detection level adjusting means 2 for adjusting the detected current to a smooth detection level 2; An induction heating type fixing device comprising: a control unit (16) for controlling the driving of the switching element based on the detected voltage values, the smoothed detection levels 1 and 2, and the detected current values 1 and 2.

According to this, in addition to the operation and effect of the above (8), by controlling the driving of the switching element based on the detected voltage, the smoothed detection levels 1 and 2 and the detected current values 1 and 2, The driving control of the switching element (17) can be performed with higher accuracy than the above (8) and (9).

(11) A fixing device (423) for fixing a toner image formed on a recording medium (PR) to the recording medium, comprising: a heated member (1) formed of a conductive member; A coil (2) disposed close to the object to be heated, for generating an induced current in the object to be heated to generate heat, and a rectifier circuit (8) and a smoothing capacitor for flowing an alternating current through the coil. (9)
A DC power supply circuit (19), a resonance circuit (2, 10) including the coil (2) and a capacitor (10), and a switching element (1).
7) and an inverter circuit (26) composed of a diode (28) connected in anti-parallel thereto, and the switching element (17)
Current detecting means (29, 18) for detecting a current flowing through the regenerative current detecting means (30, 31) for detecting a regenerative current of the inverter circuit (26), and the current detecting means in an operation state of the inverter circuit. Determining means (16) for determining a material of the object to be heated based on a current detected by (29, 18) and a detected value of regenerative current detected by the regenerative current detecting means (30, 31). An induction heating type fixing device characterized by comprising:

According to this, in the induction heating type fixing device, the coupling state between the load (1) and the induction coil (2) differs depending on the material of the load (1), whereby the inverter circuit (26)
Utilizing the difference between the value of the switch current and the value of the regenerative current flowing in
Thus, since the relationship between the load current and the regenerative current, which has a characteristic value for the load material, is determined from the detection data of the switch current and the load material is determined, the image quality of the imitation product fixing roller does not deteriorate.

Further, as a characteristic independent of the input power and frequency of the inverter circuit, the material of the load can be determined from the values of the detection data of the switch current and the regenerative current. It is not necessary to employ a complicated configuration such as correcting or changing a threshold value for determination.

(12) A fixing device (423) for fixing a toner image formed on a recording medium (1) to the recording medium, comprising: a heated member (1) formed of a conductive member; A coil (2) disposed close to the object to be heated, for generating an induced current in the object to be heated to generate heat, and a rectifier circuit (8) and a smoothing capacitor for flowing an alternating current through the coil. (9)
A DC power supply circuit (19), a resonance circuit (2, 10) including the coil (2) and a capacitor (10), and a switching element (1).
7) and an inverter circuit (26) composed of a diode (28) connected in anti-parallel thereto, and a voltage detecting means (14) for detecting a voltage at a connection point between the coil (2) and the switching element (17). ) And a current 1 flowing through the switching element (17).
Current detecting means 1 (29, 18) for detecting the current, and smoothing detection level adjusting means 1 for adjusting the detected current to the smooth detection level 1
(12), current detecting means 2 (30, 31) for detecting 2 of the current flowing through the diode (28), and the switching element based on the detected voltage value, smoothing detection level 1 and current 1.
Control means (16) for driving and controlling (17), and a current 1 detected by the current detecting means 1 (29, 18) and a current 2 detected by the current detecting means 2 (30, 31). An induction heating type fixing device, comprising: a determination unit (16) for determining a material of a body to be heated (1).

According to this, in addition to the functions and effects of the above (8) and (11), the current detecting means 1 (29, 18) for detecting the current 1 flowing through the switching element (17) is controlled by the switching element drive, It is inexpensive by sharing it with the material determination of the object to be heated.

(13) A fixing device (423) for fixing the toner image formed on the recording medium (1) to the recording medium, comprising: a heated body (1) formed of a conductive member; A coil (2) disposed close to the object to be heated, for generating an induced current in the object to be heated to generate heat, and a rectifier circuit (8) and a smoothing capacitor for flowing an alternating current through the coil. (9)
A DC power supply circuit (19), a resonance circuit (2, 10) including the coil (2) and a capacitor (10), and a switching element (1).
7) and an inverter circuit (26) composed of a diode (28) connected in anti-parallel thereto, and a voltage detecting means (14) for detecting a voltage at a connection point between the coil (1) and the switching element (17). ) And a current 1 flowing through the switching element (17).
Current detecting means 1 (29, 18) for detecting the
(28) Current detection means 2 for detecting the current 2 flowing through (28) (30, 31)
A smoothing detection level adjusting means 1 (12) for adjusting the detection current 1 to a smooth detection level; and driving the switching element (17) based on the detected voltage value, the smooth detection level 1 and the detected current 1. Control means (16) for controlling the heating target (based on the current 1 detected by the current detection means 1 (29, 18) and the current 2 detected by the current detection means 2 (30, 31); Judging means (16) for judging the material of 1)
And an induction heating type fixing device.

According to this, the above (8), (9), (1)
In addition to the effect of 1), the current flowing through the diode (28) 2
Is reduced by sharing the current detection means 2 (30, 31) for detecting the current for driving control of the switching element (17) and judging the material of the object to be heated (1).

(14) A fixing device (423) for fixing a toner image formed on a recording medium (PR) to the recording medium, comprising: a heated member (1) formed of a conductive member; A coil (2) disposed close to the object to be heated, for generating an induced current in the object to be heated to generate heat, and a rectifier circuit (8) and a smoothing capacitor for flowing an alternating current through the coil. (9)
A DC power supply circuit (19), a resonance circuit (2, 10) including the coil (2) and a capacitor (10), and a switching element (1).
7) and an inverter circuit (26) composed of a diode (28) connected in anti-parallel thereto, and a voltage detecting means (14) for detecting a voltage at a connection point between the coil (2) and the switching element (17). ) And a current 1 flowing through the switching element (17).
Current detection means 1 (29, 18) for detecting the current, and smooth detection level adjustment means 1 for adjusting the detected current to the smooth detection level 1
(12), a current detecting means 2 (30, 31) for detecting a current 2 flowing through the diode (28), a smooth detection level adjusting means 2 for adjusting the detected current to a smooth detection level 2, The control means (16) for controlling the drive of the switching element (17) based on the detected voltage value, the smoothing detection levels 1 and 2, and the currents 1 and 2, and the current detection means 1 (29, 18). Determining means (16) for determining the material of the object to be heated (1) based on the current 1 detected by the current detecting means 2 and the current 2 detected by the current detecting means 2 (30, 31). Induction heating type fixing device.

According to this, the above (1), (2),
In addition to the effects of (3) and (4), the switching element (1
7) Current detection means 1 (29, 18) for detecting current 1 flowing through
And the current detecting means 2 (30, 31) for detecting the current 2 flowing in the diode (28) is shared by the drive control of the switching element (17) and the material judgment of the object to be heated (1). Becomes

[0052]

FIG. 1 is a block diagram of a control system of an induction heating type fixing apparatus to which the present invention is applied. here,
Members having the same functions or corresponding members as those in the conventional example shown in FIG. 15 are denoted by the same reference numerals as those in the respective drawings described above, and description thereof will be omitted.

In the induction heating type fixing device shown in FIG. 1, a thermal fuse 4 as a safety protection component is disposed on or near the surface of the object 1 to be heated. 4 via
If the temperature of the object to be heated 1 becomes abnormal, the temperature fuse 4
As a result, the power supply current is cut off.

The smoothing capacitor 9 has a capacitance of 10 μF or less in the present apparatus in order to prevent the applied high frequency current from being generated at a high frequency and to reduce the cost of the apparatus. This is because, for this device, the alternating current (A
C100V) is rectified and applied to the coil 2 as it is. As a result, the LC output from the DC power supply circuit 19 including the rectifier circuit 8 and the smoothing capacitor 9 and comprising the coil 2 and the resonance capacitor 10
The current applied to the resonance circuit has a full-wave rectified waveform as shown in FIG.

The high-frequency current is supplied to the DC power supply circuit 19.
And a switch 17 connected in series to the LC resonance circuit (2 + 10), which is a switching element composed of, for example, a transistor, an FET, or an IGBT, and the like. The ON timing of the switch 17 is determined by the voltage detection circuit 14, and the voltage detection circuit 14
Is detected, and in this example, it is almost 0 V
At this point, an ON signal is output to the control circuit 16 and the switch 17 is turned on via the drive circuit 15.

On the other hand, when the switch 17 is turned off,
It is determined by the current flowing through the switch 17 detected by the current detection circuit 18. That is, when the current flowing through the switch 17 reaches the instantaneous value (current value) of the time series envelope level of the peak value of the detection current generated by the smoothing current detection level circuit 12, the off signal is sent to the control circuit 16 so as to turn off. Then, the switch 17 is turned off via the drive circuit 15. As described below, the envelope level is proportional to the output voltage waveform of the DC power supply circuit 19 (FIG. 3).

When the switch 17 is repeatedly turned on and off, a high-frequency current flows through the coil 2 and induction heating of the object to be heated 1 is performed. That is, the high frequency (switching frequency) applied to the coil is determined by this switching operation.

Here, the function of the smoothing current detection level circuit 12 will be described. FIG. 3 shows the current flowing through the switch 17 by a solid line. The peak of one waveform of the full-wave rectified voltage waveform (the coil applied voltage V in FIG. 3) output from the DC power supply circuit 19 is also enlarged. It is shown. The voltage applied to the coil 2 is V, the inductance of the coil 2 is L,
Assuming that the coil current is i and the on-time in the above-described on / off repetition of the switch 17 is Δt, the following equation (1) generally holds: Δi / Δt = V / L (1).

Here, since the voltage V applied to the coil 2 is a full-wave rectified waveform, if the amplitude of the power supply voltage is V0, it can be set as the following (2): V = V0 | sin (ωt) | .

By substituting equation (2) into equation (1), the following equation (3) is obtained: Δi / Δtconst = (V0 | sin (ωt) |) / Lconst (3)

Therefore, when Δt, which is proportional to the reciprocal of the switching frequency, is constant, it can be seen that the following equation (4) is obtained: Δi = i 0 | sin (ωt) | (4)

Therefore, when Δt is constant, V and Δi can be made proportional. Here, i0 is the amplitude of the coil current detection level (dotted line in FIG. 3), and V0 is the amplitude of the power supply voltage (dotted line in FIG. 3).

That is, in the present apparatus, the smoothing current detection level circuit 12 smoothes the current value (current peak value during Δt) detected by the current detection circuit 18 (enlarged dashed line in FIG. 3). ). This envelope level is
If Δt is constant, the output voltage of DC power supply circuit 19 (FIG.
Upper two-dot chain line).

When the current value detected by the current detection circuit 18 reaches the envelope level generated by the smoothing current detection level circuit 12, the control circuit 16
Turn 7 off. As a result, the ON time Δt becomes constant, and even if the voltage applied to the coil changes, the switch 17 is repeatedly turned on and off at a constant frequency. Instead of generating the time-series envelope level of the switch current in the circuit 12, the output voltage (FIG. 2) of the DC power supply circuit 19 is detected, and it is divided or amplified and used in place of the above-mentioned envelope level. Is also good.

In FIG. 1, the control circuit 16 determines whether the temperature of the heating target 1 is fixed by the temperature detected by a thermistor (not shown) disposed in contact with or in the vicinity of the heating target 1. The on-time is corrected in accordance with the deviation of the detected temperature from the target temperature so that the required temperature is obtained. That is, the timing of turning off is delayed or made earlier. Alternatively, this correction may be performed by raising and lowering the envelope level according to the deviation of the detected temperature.

The circuit DC power supply 11 is
4, a simple stabilized power supply for supplying DC power to the drive circuit 15, the control circuit 16, and the current detection circuit 18 (however, wiring paths to these components are not shown in the figure).

FIG. 4 collectively shows a heating output characteristic, a switching frequency characteristic, and a temperature characteristic of an object to be heated in the conventional example and the present invention. As can be seen from this figure, the heating output characteristics of the present invention and the conventional example are both constant. The switching frequency characteristic of the present invention is a constant frequency in the non-audible band, but in the conventional example, the frequency fluctuates and falls within the audible band (20 kHz or less).
The temperature characteristic of the object to be heated shows a constant rising speed in both the present invention and the conventional example. As described above, in the conventional example, there are disadvantages such as generation of noise. On the other hand, when the present invention is applied, all of the heating output characteristic, the switching frequency characteristic, and the temperature characteristic of the object to be heated are good. Become.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

Next, an embodiment of the present invention will be described with reference to the drawings. Note that members having the same functions are denoted by the same reference numerals as in the respective drawings described above, and description thereof will be omitted.

[0070]

FIG. 5 shows an image processing apparatus according to an embodiment of the present invention. This embodiment is a digital full-color copying machine. Color image reading device (hereinafter referred to as document scanner) 200
Is an image of the original 180 on the contact glass 202,
Illumination lamp 205, mirror group 204A, 204B, 20
4C and the like, and the color sensor 2 via the lens 206.
07, the color image information of the original is converted into, for example, blue (hereinafter, referred to as B) and green (hereinafter, referred to as G).
And red (hereinafter, referred to as R) color-separated light, and converted into an electrical image signal. Color sensor 207
Is composed of a three-line CCD sensor in this example, and reads B, G, and R images for each color. Scanner 20
0, color conversion processing is performed by an image processing unit (20: FIGS. 2 and 3) (not shown) based on the B, G, and R color separation image signal intensity levels obtained in step S0.
, Cyan (hereinafter, referred to as C), magenta (hereinafter, referred to as M), and yellow (hereinafter, referred to as Y) are obtained.

Using the color image data, a color image recording device (hereinafter referred to as a color printer) 4 described below
00, the images of Bk, C, M, and Y are overlaid on the intermediate transfer belt and transferred to a transfer sheet. The document scanner 200 receives a scanner start signal synchronized with the operation of the color printer 400, and scans a document in the direction of the left arrow by an illumination / mirror optical system including an illumination lamp 205 and mirror groups 204A, 204B, and 204C. One color image data is obtained for each scan. Each time, while sequentially visualizing the color printer 400,
These are superposed on the intermediate transfer belt to form four full-color images.

The writing optical unit 401 as an exposure unit of the color printer 400 is
Is converted into an optical signal, optical writing corresponding to the original image is performed, and an electrostatic latent image is formed on the photosensitive drum 414. The optical writing optical unit 401
It comprises a laser light emitter 441, a light emission drive controller (not shown) for driving the light emission, a polygon mirror 443, a rotation motor 444 for rotating the polygon mirror 443, an fθ lens 442, a reflection mirror 446, and the like. Photoconductor drum 41
4 rotates counterclockwise as shown by the arrow,
Around the photosensitive member cleaning unit 421, a neutralizing lamp 414M, a charger 419, a potential sensor 414D for detecting a latent image potential on the photosensitive drum, a selected developing device of the revolver developing device 420, and a developing density pattern detector 414P, an intermediate transfer belt 415, and the like are arranged.

The revolver developing device 420 includes a BK developing device 420K, a C developing device 420C, an M developing device 420M, and a Y developing device 420Y, and a revolver rotating drive for rotating each developing device in a counterclockwise direction as indicated by an arrow. (Not shown). In order to visualize the electrostatic latent image, each of these developing devices rotates developing sleeves 420 KS and 420 which rotate by contacting the ears of the developer with the surface of the photosensitive drum 414.
CS, 420MS, 420YS, and a developing paddle that rotates to assemble and stir the developer. In the standby state, the revolver developing device 420 is set at a position where development is performed by the BK developing device 420, and when a copy operation is started, reading of BK image data starts at a predetermined timing by the original scanner 200,
Based on the image data, optical writing by a laser beam, that is, latent image formation starts. Hereinafter, the electrostatic latent image based on the Bk image data is referred to as a Bk latent image. The same applies to each of the C, M, and Y image data. In order to enable development from the leading end of the Bk latent image, before the leading end of the latent image reaches the developing position of the Bk developing device 420K, the rotation of the developing sleeve 420KS is started to develop the Bk latent image with Bk toner. . And after that,
The developing operation of the Bk latent image area is continued, but the rear end of the latent image is
Immediately after passing the latent image position, the Bk developing device 42
The revolver developing device 420 is driven to rotate from the development position at 0K to the development position at the next color developing unit. This rotation operation is completed at least before the leading end of the latent image based on the next image data arrives.

When the image forming cycle is started, the photosensitive drum 414 rotates counterclockwise as indicated by an arrow, and the intermediate transfer belt 415 is rotated clockwise by a drive motor (not shown). Move. Intermediate transfer belt 41
5, the BK toner image formation, the C toner image formation, the M toner image formation, and the Y toner image formation are sequentially performed, and finally, on the intermediate transfer belt 415 in the order of BK, C, M, and Y. , A toner image is formed. The formation of the BK image is performed as follows.

That is, the charger 419 uniformly charges the photosensitive drum 414 with a negative charge to about -700 V by corona discharge. Then, the laser diode 441
Performs raster exposure based on the Bk signal. When the raster image is exposed in this manner, in the initially exposed portion of the photosensitive drum 414 that is uniformly charged, the charge proportional to the amount of exposure light disappears, and an electrostatic latent image is formed. The toner in the revolver developing device 420 is negatively charged by stirring with the ferrite carrier, and the BK developing sleeve 420KS of the developing device is
A negative direct current potential and an alternating current are biased by a power supply circuit (not shown) to the fourteen metal base layers. As a result, the toner does not adhere to the portion of the photosensitive drum 414 where the charge remains, and the Bk toner is adsorbed to the portion having no charge, that is, the exposed portion, and the Bk visible light similar to the latent image is obtained. An image is formed. The intermediate transfer belt 415 includes a drive roller 415D, a transfer opposing roller 4
15T, the cleaning opposing roller 415C, and a group of driven rollers, which are rotated and driven by a drive motor (not shown).

The B formed on the photosensitive drum 414
The k toner image is transferred by a belt transfer corona discharger (hereinafter, referred to as a belt transfer unit) 416 to the surface of the intermediate transfer belt 415 that is driven at a constant speed in contact with the photoconductor. Hereinafter, the photosensitive drum 414 to the intermediate transfer belt 4
Transfer of the toner image onto the transfer belt 15 is referred to as belt transfer. Some untransferred residual toner on the photoconductor drum 414 is cleaned by the photoconductor cleaning unit 421 in preparation for reuse of the photoconductor drum 414. The toner collected here is
The toner is stored in a waste toner tank (not shown) via a collection pipe.

On the intermediate transfer belt 415, the Bk, C, M, and Y toner images formed sequentially on the photosensitive drum 414 are sequentially aligned on the same surface, and a four-color superposed belt transfer image is formed. After that, batch transfer is performed on transfer paper by a corona discharge transfer device. By the way, the photosensitive drum 41
On the fourth side, the process proceeds to the C image forming process after the BK image forming process.
The reading of the C image data by 00 starts, and the formation of the C latent image is performed by writing the laser light with the image data. The C developing device 420C rotates the revolver developing device with respect to the developing position after the trailing edge of the previous Bk latent image has passed and before the leading end of the C latent image has arrived.
The latent image is developed with C toner. Thereafter, the development of the C latent image area is continued, but when the rear end of the latent image has passed, the revolver developing device 420 is driven as in the case of the Bk developing device, and the C developing device 420C is sent out. M developing unit 42
0M is located at the development position. This operation is also performed before the leading end of the next M latent image reaches the developing unit. Note that M
In the process of forming each image of Y and Y, the operations of reading image data, forming a latent image, and developing are performed in the above-described B mode.
The description is omitted because it is in accordance with the steps of the k image and the C image.

The belt cleaning device 415U includes an inlet seal, a rubber blade, a discharge coil, and a mechanism for contacting and separating the inlet seal and the rubber blade. 1
While the second, third, and fourth color images are being transferred to the belt after the Bk image of the color is transferred to the belt, the entrance seal, the rubber blade, and the like are separated from the intermediate transfer belt surface by the blade contact / separation mechanism. .

A paper transfer corona discharger (hereinafter, referred to as a paper transfer device) 417 uses an AC corona discharge method to transfer the superposed toner image on the intermediate transfer belt 415 to transfer paper.
+ DC or a DC component is applied to the transfer paper and the intermediate transfer belt.

Transfer paper is stored in the transfer paper cassette 482, and is fed and conveyed in the direction of the registration roller pair 418 R by the paper feed roller 483. Note that reference numeral 412B
Reference numeral 2 denotes a paper feed tray for manually feeding OHP paper or thick paper. At the time when the image formation is started, the transfer paper is fed from the paper feed tray and the registration roller pair 418R is used.
Waiting at the nip. Then, the paper transfer device 417
When the leading edge of the toner image on the intermediate transfer belt 415 is approaching, the registration roller pair 418R is driven so that the leading edge of the transfer paper coincides with the leading edge of the image, and the paper and the image are aligned. In this way, the transfer paper is superimposed on the color superimposed image on the intermediate transfer belt, and passes over the paper transfer unit 417 connected to the positive potential. At this time, the transfer paper is charged with a positive charge by the corona discharge current, and most of the toner image is transferred onto the transfer paper. Subsequently, when the transfer paper passes through a separation static eliminator by a static elimination brush (not shown) disposed on the left side of the paper transfer device 417, the transfer paper is discharged, separated from the intermediate transfer belt 415, and moved to the paper transport belt 422. The transfer paper on which the four-color superimposed toner image is collectively transferred from the intermediate transfer belt surface is conveyed to a fixing device 423 by a paper conveyance belt 422, and the toner image is formed at a nip portion between a fixing roller and a pressure roller controlled to a predetermined temperature. The sheet is melted and fixed, sent out of the main body by a discharge roll pair 424, and stacked face up on a copy tray (not shown).

The photosensitive drum 414 after belt transfer
Is cleaned by a photoreceptor cleaning unit 421 including a brush roller, a rubber blade, and the like.
Further, the charge is uniformly removed by the charge removing lamp 414M. Further, the intermediate transfer belt 415 after transferring the toner image to the transfer paper
Again, the blade is pressed by the blade contact / separation mechanism of the cleaning unit 415U to clean the surface.
In the case of the repeat copy, the operation of the scanner and the image formation on the photosensitive member follow the fourth-color image process of the first sheet, and proceed to the second-color image process at a predetermined timing. In the case of the intermediate transfer belt 415, the second Bk toner image is belt-transferred to an area whose surface has been cleaned by the belt cleaning device, following the batch transfer process of the first four-color superimposed image onto transfer paper. So that Thereafter, the operation is the same as that of the first sheet.

The color copying machine shown in FIG. 5 is provided from a host such as a personal computer via a LAN or a parallel I / F.
When the print data is given through the MFP, the color data can be printed out (image output) by the color printer 400, and the image data read by the original scanner 200 can be transmitted to a remote facsimile, and the received image data can be printed out. Is a color copier. This copier is connected to a public telephone network via a private branch exchange PBX, and can communicate with a facsimile communication and a management server of a service center via the public telephone network.

FIG. 6 shows an electric system of the copying machine shown in FIG. Document scanner 200 for optically reading a document
In the reading unit, reflected light of the lamp irradiation on the document is condensed on the light receiving element 207 by a mirror and a lens in the reading unit. The light receiving element (CCD in this embodiment) is a sensor
An image signal converted to an electric signal in the CCD is provided in a board unit SBU (hereinafter simply referred to as SBU).
After being converted into a digital signal, that is, read image data on the SBU, the image data is output from the SBU to the image processor 200.

The system controller 106 in the multifunction controller 100 and the process controller in the printer 400 communicate with each other via a parallel bus Pb and a serial bus Sb. The image processing 300 internally performs data format conversion for a data interface between the parallel bus Pb and the serial bus Sb.

The read image data from the SBU is transferred to the image processing 300, and the image processing is performed for the signal deterioration due to the quantization into the optical system and the digital signal (the signal deterioration of the scanner system: the read image data due to the scanner characteristics). The image data is transferred to the copying function controller 100 and written into the memory MEM. Alternatively, a process for printer output is performed and the result is given to the printer 400.

That is, the image processing 300 includes a job for storing the read image data in the memory MEM for reuse and a video data control V without storing the image data in the memory MEM.
There is a job for outputting to DC (hereinafter simply referred to as VDC) and for forming and outputting an image with the laser printer 400. Memory ME
As an example of storing the data in the M, when copying a plurality of originals, the reading unit is operated only once, the read image data is stored in the memory MEM, and the stored data is read a plurality of times. As an example in which the memory MEM is not used, when only one document is copied, it is only necessary to process the read image data as it is for the printer output, so that there is no need to write in the memory MEM.

First, when the memory MEM is not used, the image processing 300 performs image reading correction on read image data and then performs image quality processing for conversion to area gradation.
The image data after the image quality processing is transferred to the VDC. With respect to the signal changed to the area gradation, post-processing related to dot arrangement and pulse control for reproducing dots are performed by VDC,
The reproduced image is formed on the transfer paper in the image forming unit of the laser printer 400.

When additional processing, for example, rotation in the image direction, synthesis of images, and the like are performed when the data is stored in the memory MEM and read out from the memory MEM, the image data subjected to the image reading correction is transmitted via the parallel bus Pb. It is sent to the image memory access control IMAC (hereinafter simply referred to as IMAC). Here, access control of image data and a memory module MEM (hereinafter simply referred to as MEM) is performed based on the control of the system controller 106, and an external personal computer PC (hereinafter simply referred to as PC).
) (Character code / character bit conversion) and compression / expansion of image data for effective use of memory. The data sent to the IMAC is stored in the MEM after data compression, and the stored data is read as necessary. The read data is expanded, returned to the original image data, and returned from the IMAC to the image processing 300 via the parallel bus Pb.

When the process returns to the image processing 300, image quality processing and pulse control at VDC are performed, and a visual image (toner image) is formed on transfer paper in the image forming unit.

The fax transmission function, which is one of the composite functions,
The image data read by the original scanner 200 is subjected to image processing 30.
At 0, the image is read and corrected and transferred to the FAX control unit FCU (hereinafter simply referred to as FCU) via the parallel bus Pb. The FCU converts data to the public line communication network PN (hereinafter simply referred to as PN) and faxes it to the PN.
Send as data. In FAX reception, line data from the PN is converted into image data by the FCU, and is transferred to the IPP via the parallel bus Pb and the CDIC. In this case, no special image quality processing is performed, dot rearrangement and pulse control are performed in the VDC, and a visible image is formed on the transfer paper in the image forming unit.

In a situation where a plurality of jobs, for example, a copy function, a facsimile transmission / reception function and a printer output function, operate in parallel, the allocation of the reading unit, the image forming unit and the right to use the parallel bus Pb to the job is performed by the system controller. Controller 106 and the process controller.

The process controller of the printer 400 controls the flow of image data, and the system controller 106 controls the entire system and manages the activation of each resource. The function selection of this digital multifunction copying machine is made by selecting and inputting through the operation board OPB, and setting the processing contents such as the copy function and the FAX function.

A control circuit 16, which will be described later, of the fixing unit 423 (electrical system of the fixing device 423) is controlled by the system controller 106 via the serial bus Sb, and notifies the system controller 106 of status information in the fixing unit 423. .

FIG. 7 shows a mechanism cross section of the fixing device 423. The fixing device 423 includes a fixing roller 1, which is a heating object, that is, a body to be heated, rotatably driven in the direction of arrow a, and a fixing roller 1 provided in pressure contact with the fixing roller 1.
And a pressure roller 6 that rotates following the rotation of the roller.
The fixing roller 1 is a conductive hollow cylindrical pipe made of a conductive material such as a carbon steel pipe, a stainless alloy pipe, or an aluminum alloy pipe. A mold layer is formed. The fixing roller 1 is preferably made of a conductive magnetic member (for example, a carbon steel pipe or a stainless alloy pipe). On the other hand, the pressure roller 6 is formed by forming a silicon rubber layer 62 which is a surface releasable heat-resistant rubber layer around a shaft core 61.

As shown in FIGS. 8A and 8B, a coil 2 for generating an induction current in the fixing roller 1 and causing the fixing roller 1 to generate heat is provided inside the fixing roller 1 in the form of a prism. A plurality of coils are wound around the core 3. The coil 2 is fixed with a mandrel (not shown) with a slight gap between the coil 2 and the fixing roller 1 so that the fixing roller 1 can rotate. The coil 2 is wound around the core 3 using a single or litz copper wire having a diameter of 0.8 mm and having a fusion layer and an insulating layer on the surface, and the core 3 is, for example, a ferrite core or a laminated core. Consists of

Above the fixing roller 1, a thermistor (not shown) for detecting the temperature of the fixing roller, and as a safety mechanism when the temperature rises abnormally, energizing the coil 2 when an abnormally high temperature is detected. Is provided. Further, the tip is a fixing roller 1
Is provided with a separating claw 5 (FIG. 7) provided so as to be in sliding contact with the surface.

The fixing roller 1 has sliding bearings formed on the outer periphery of both ends thereof, and is rotatably mounted on the fixing unit frame. Further, the fixing roller 1
A drive gear (not shown) is fixed to one end, and is driven to rotate by a drive source (not shown) such as a motor connected to the drive gear.

FIG. 9 shows an electric system of the fixing device 423. DC power supply circuit 19 for supplying power to inverter circuit 26
Rectifies the output of the AC input circuit 13 and supplies the rectified output between the DC power supply lines 23 and 25 via the smoothing choke coil 22. 9 are connected.

The AC input circuit 13 is provided with an AC power supply line for receiving the output of a commercial AC power supply through a power supply plug, a power supply switch and a fuse. A varistor and a noise prevention capacitor are connected between the power supply lines. is there.

The inverter circuit 26 is of a single-end type. The heating coil 2 as a resonance coil and the collector and emitter of a switch 17 which is an IGBT as a switching element are connected in series between the DC power supply lines 23 and 25. And flywheel diode 2
8 is connected in an anti-parallel state with the switch 17, and the resonance capacitor 10 is connected in parallel with the heating coil 2. The heating coil 2 links a high-frequency magnetic field to the fixing roller 1.

The control circuit 16 controls the on / off of the switch 17 of the inverter circuit 26 via the PWM pulse and the drive circuit 15, and the connection point between the coil 2 and the switch 17 detected by the voltage detection circuit 14. Of the PWM pulse at the timing of 0 V
The start point of the cycle is determined, and the switch 17 is turned on at this start point. That is, the resonance voltage given by the voltage detection circuit 14 is 0.
At the timing of V, the oscillation circuit 16a generates an ON instruction pulse and supplies it to the output control circuit 16c.

A current detection circuit 18 as a switch current detection means detects a switch current based on a current detection voltage of a current transformer 29 in the inverter 26 and a current detection signal Sin having a voltage level corresponding to the detected current value.
With the output control circuit 16c and the smoothing current level detection circuit 12
Give to.

The smoothing current level detection circuit 12 smoothes the current detection signal Sin, generates a voltage representing the time series envelope level of the current detection signal Sin, and supplies the voltage to the output circuit 16c. When the output voltage of the DC power supply circuit 19 is as shown by a two-dot chain line in FIG. 3, the current detection signal Sin becomes a sawtooth wave shown by a solid line in FIG.
3 is indicated by a chain line, and is substantially proportional to the output voltage of the DC power supply circuit 19.

The regenerative current detecting circuit 31 detects a regenerative current based on an induced voltage of the current transformer 30 interposed so as to detect a current flowing through the flywheel diode 28, and detects a regenerative current of a voltage proportional to the regenerative current level. The signal Sk is provided to the output control circuit 16c.

The thermistor 20 detects the temperature of the fixing roller 1 and gives a temperature signal to the arithmetic circuit 16b. Arithmetic circuit 1
6b calculates the deviation of the detected temperature from the target temperature (data) set therein, and gives a temperature deviation signal Vba to the output control circuit 16c. Here, the temperature deviation signal Vb
a is a voltage Vba that becomes lower as the detected temperature is lower than the target temperature, and becomes higher as the detected temperature becomes higher.

Output control circuit 16c in the steady driving state
When the oscillation circuit 16a generates an ON instruction pulse, the PWM pulse output terminal to the drive circuit 15 is set to the high level H for the ON instruction in response to the ON instruction pulse, and the current detection signal Sin is biased with the temperature deviation signal Vba. That is, the current detection signal S
in, a correction bias Vbb corresponding to the roller material described later is added, and when the resulting voltage (Sin + Vba + Vbb) reaches the envelope level voltage of the smoothing current level detection circuit 12, the driving circuit 1
5, the PWM pulse output terminal is returned to the low level L of the OFF instruction. As a result, the drive circuit 15 is provided with a PWM pulse instructing on / off of the switch 17, and the drive circuit 15 turns on the switch 17 when the PWM pulse is H and turns off the switch 17 when the PWM pulse is L.

Assuming that the temperature of the fixing roller 1 does not change in accordance with the target temperature, the temperature deviation signal is a constant value, and the output voltage of the DC power supply circuit 19 is shown by a two-dot chain line in FIG. Sometimes, the current detection signal Sin becomes a sawtooth wave shown by a solid line in FIG.
3 is indicated by a chain line, and is substantially proportional to the output voltage of the DC power supply circuit 19.

When the temperature of the fixing roller 1 is low, since the temperature deviation signal is low, the H period of the PWM pulse, that is, the on-time is lengthened, the current detection signal Sin indicated by the solid line in FIG. 3 rises, and the time series envelope level becomes The output voltage of the DC power supply circuit 19 shown in FIG. 3 is substantially proportional to the output voltage of the DC power supply circuit 19 shown in FIG. 3 unless the level of the temperature deviation signal is changed. The proportional relationship with the output voltage of No. 19 does not change. That is, switch 1
The on-time of 7 is substantially constant.

While the temperature of the fixing roller 1 is changing,
Since the temperature deviation signal changes, the ON time of the switch 17 changes correspondingly. However, since the change in the temperature deviation signal in one cycle of the output voltage fluctuation of the DC power supply circuit 19 is insignificant, the current Sin flowing through the switch 17 becomes small in the microscopic time of about one cycle. It can be considered that the output voltage of the power supply circuit 19 is substantially proportional to the output voltage. That is, the on-time can be regarded as substantially constant.

The output control circuit 16c also has a function as a roller material determining means, and determines the material of the roller R as described later, and switches the inverter circuit 26 according to a control pattern corresponding to the determination result. 17 is turned on / off. At this time, it is also determined whether or not the roller 1 as a load exists in the immediate vicinity of the coil 2. When it is determined that the roller 1 is absent (no load), the coil 2 is not energized. The output control circuit 16c
The determination of the roller material is performed immediately after the operating voltage is applied to itself.

That is, when the operation voltage is applied and the initialization of itself and the initialization of the fixing device 423 are completed, the output control circuit 16c first starts to output the PWM pulse of the lowest on-duty to the drive circuit 15, and then turns on. Increase the duty gradually. That is, the switch current Sin is gradually increased. By starting the output of the PWM pulse,
The switch 17 starts on / off operation, and the heating coil 2
Operate in resonance with the resonance capacitor 10. At this time, during the ON period of the switch 17, the DC power supply circuit 19
Current flows from the heating coil 2 to the heating coil 2, and during the switch 17 off period, a resonance circuit is formed by the heating coil 2 and the resonance capacitor 10, and current (power) is exchanged between the two. That is, a resonance current flows. In this state,
Charging / discharging of the resonance capacitor 10 was performed to the heating coil 2. In particular, when the resonance capacitor 10 was discharged, the voltage between the collector and the emitter of the switch 17 (IGBT) became almost zero, and the discharge from the resonance capacitor 10 was stopped. At this time, a regenerative current flows through the flywheel diode 30 and the heating coil 2 to the smoothing capacitor 6 on the DC power supply circuit 2 side.

At this time, the regenerative current flowing through the flywheel diode 30 is detected as a voltage signal by the current transformer 30 and output as a regenerative current signal Sk to the output control circuit 16c by the regenerative current detection circuit 25. When the drive of the inverter circuit 26 is controlled as described above, the switch current input from the DC power supply circuit 19 is detected as a voltage signal by the current transformer 29, and the current detection circuit 18 outputs a signal Sin indicating the switch current. It is output to the output control circuit 16c.

The output control circuit 16c converts the switch current detection signal Sin supplied from the current detection circuit 18 into switch current detection data proportional to the input current, as the regenerative current detection signal Sk supplied from the regenerative current detection circuit 31.
Is treated as regenerative current detection data proportional to the regenerative current. For example, when the switch current detection data value is “100”, the switch current is about 8 A, and when the regenerative current detection data value is “125”, the regenerative current has a peak value of about 40 A. I have.

Next, the operation of determining the material of the fixing roller 1 as a load will be described. The output control circuit 16c performs a determination operation based on the following detection principle from the switch current Sin output from the current detection circuit 18 and the regenerative current Sk output from the regenerative current detection circuit 31.

First, as a material suitable for the fixing roller 1, for example, a material made of iron or stainless steel (SUS) is recommended, and conversely, a material having a high conductivity like aluminum is used. In such a case, the regenerative current becomes large and the heat generation efficiency decreases, and in this case, the roller is considered to be inappropriate. Further, even if the material is iron or stainless steel, it is necessary to exclude a load that is improper in size as a fixing roller and substantially in a no-load state as an improper one.

Now, with the above-mentioned materials,
There is a relationship as shown in FIG. 10 between the switch current Sin and the regenerative current Sk. That is, the inverter circuit 26
Is started, the on-duty of the PWM pulse is gradually increased, and the switch current Sin and the regenerative current Sk are increased.
Gradually increases, the value of the ratio Sk / Sin according to the material of the fixing roller 1, that is, the slope of the characteristic line indicating the relationship between the two is determined substantially according to the material, and the input power (Sin) increases. At the same time, the switch current and the regenerative current increase along the characteristic line having the slope.

For example, when an appropriate iron roller is present as the fixing roller 1, the switch current Sin tends to be larger than the regenerative current Sk. Conversely, when a stainless steel roller is used, the switch current Sin becomes larger. The regenerative current Sk tends to be larger than Sin. In addition, when aluminum, which is an example of an inappropriate roller, is used or when there is no load, only the regenerative current Sk increases and the switch current Sin hardly increases. Such a tendency is that even if the input power or frequency to the inverter circuit 26 fluctuates, it has stable characteristics without being greatly affected by such fluctuation.

Therefore, as shown in FIG. 11, the output control circuit 16c increases the on-duty of the PWM pulse applied to the drive circuit 15 at the first predetermined speed until the switch current Sin and the regenerative current Sk are stabilized (time t1). Let
Thereafter, the current is further increased at the second predetermined speed, and PW is maintained until the detection data value of the regenerative current Sk reaches the predetermined level K.
The on-duty of the M pulse is increased ((c) in FIG. 11).

When the regenerative current Sk reaches the predetermined level K, the output control circuit 16c compares the switch current Sin at that time with predetermined thresholds L1 and L2 for determination. At this time, the fixing roller 1
Is an iron roller, for example, when the switch current Sin exceeds the threshold value L1, it is determined that the iron roller is appropriate. If the switch current Sin is equal to or less than the threshold value L1 but exceeds the threshold value L2, it is determined that the roller is a stainless roller. Further, when the switch current Sin is equal to or less than the threshold value L2, it is determined that there is no inappropriate roller or no roller.

In the above case, the time required for the regenerative current Sk to reach the predetermined level K differs depending on the material of the fixing roller 1. For example, in the case of the iron roller, the time is t2, whereas the time of the stainless steel roller is t2. In this case, it is time t3 later than that. This indicates that the degree of increase in the regenerative current Sk differs depending on the material of the roller. Therefore, threshold values for both the switch current Sin and the regenerative current Sk are set in the output control circuit 16c, and the on-duty of the PWM pulse is gradually increased to set either the switch current Sin or the regenerative current Sk. The material may be determined when the threshold value is exceeded.

When the above-mentioned material judgment is completed, the output control circuit 16c sets the correction bias voltage Vbb corresponding to the material.
Is added to the value Sin + Vba obtained by adding the temperature deviation signal Vba described above to the current detection signal Sin, and the process proceeds to the fixing temperature control in the steady state. That is, when the oscillation circuit 16a generates the ON instruction pulse, the driving circuit 15
The PWM pulse output terminal to the drive circuit 15 is turned off when the added value (Sin + Vba + Vbb) reaches the envelope level voltage of the smoothing current level detection circuit 12. , The PWM pulse output to return to the low level L of Thus, the fixing roller 1 is controlled at a constant temperature with appropriate response characteristics.

When it is determined that an inappropriate roller or no roller is present, the output control circuit 16c maintains the PWM pulse output terminal to the drive circuit 15 at the off instruction level L and does not energize the coil 2. . At the same time, the system controller 106 is notified of the fixing roller abnormality. In response to this, the system controller 106 turns on the serviceman call indicator light (abnormality notification light) on the operation display board OPB, enters the image forming prohibited state, and does not respond to the image forming instruction.

Embodiment 2 FIG. 12 shows a second embodiment of the electric system of the fixing device according to the present invention. In this example, the electric system shown in FIG.
The input voltage detection circuit 34 is added, and the AC output voltage of the AC input circuit 13 is divided by the voltage dividing resistors 32 and 33 and applied to the input voltage detection circuit 34. The input voltage detection circuit 34 outputs the input voltage detection signal Sv representing the AC input voltage to the arithmetic circuit 16b.
Give to. An operation circuit 16b is provided from the operation display board OPB.
Then, a fixing temperature (high, medium, low) designation Sps is given via the system controller 106 (FIG. 6).

The arithmetic circuit 16b of the second embodiment calculates a deviation Vba of the detected temperature from the target temperature corresponding to the fixing temperature (high, medium, low) specified Sps, and furthermore, calculates a reference value (100 V) of the AC input voltage. Is calculated, and a reference signal Sref representing the sum Vba + Vvi of the difference is supplied to the output circuit 16c. Here, the temperature deviation signal Vba is a voltage Vba that becomes lower as the detected temperature is lower than the target temperature, and becomes higher as the detected temperature becomes higher. The AC input deviation signal Vvi is based on the input voltage detection signal Sv with respect to the reference value (100 V) of the AC input voltage.
Is lower as the detection signal Sv becomes higher, and becomes higher as the detection signal Sv becomes higher.

Output control circuit 16c in the steady driving state
When the oscillation circuit 16a generates an ON command pulse, the PWM pulse output terminal to the drive circuit 15 is set to the high level H for the ON command in response to the ON command pulse, and the current detection signal Sin is biased with the reference signal Sref. Current detection signal Si
n and the correction bias Vbb corresponding to the roller material described above, and when the resulting voltage (Sin + Vba + Vbb + Vvi) reaches the envelope level voltage of the smoothing current level detection circuit 12, the driving circuit 15 The PWM pulse output terminal to the low level L of the OFF instruction. As a result, the drive circuit 15 includes the switch 1
When a PWM pulse instructing ON / OFF of 7 is given, the drive circuit 15 turns on the switch 17 when the PWM pulse is H and turns off when the PWM pulse is L.

For example, if the reference value of the AC input voltage is 10
In the case of 0V, the output control circuit 16c switches the PWM pulse output terminal to the drive circuit 15 to the off instruction level L when the input voltage detection signal Sv is out of the range of 80V or more and 120V or less.
And the coil 2 is not energized. At the same time, the system controller 106 is notified of the fixing roller abnormality.
In response to this, the system controller 106 turns on the serviceman call indicator light (abnormality notification light) on the operation display board OPB, enters the image forming prohibited state, and does not respond to the image forming instruction.

In the above-described first and second embodiments, when the output control circuit 16c determines an inappropriate roller or a no-load state in determining the material of the fixing roller 1, the output heating circuit 16c stops the subsequent heating operation. In the modified example, the determination operation is repeatedly performed at intervals of, for example, several seconds, and if the determination result is inappropriate even after a predetermined time has elapsed, the start of the heating operation is stopped. As a result, for example, even if the user inadvertently turns on the operation switch for starting heating before attaching the fixing roller, an unusual heating operation starts when an appropriate roller is attached.

The present invention is not limited to the above-described embodiment or modification, but can be further modified or improved. For example, the switch current Sin and the regenerative current Sk are used as instantaneous values for determining the roller material, but an average value or a smoothed value may be used. When the no-load state (no roller) is determined, the repetitive determination operation may be adopted as necessary. As the switching element 17, besides the IGBT, a field effect transistor, a bipolar transistor, or the like can be used.

In the application of the present invention, the shape of the induction heating coil 2 and the core to which it is mounted,
The arrangement and the like are not limited to the above-described embodiment. For example, as shown in FIG. 13, the shape of the core and the coil may be such that the coil 2 is spirally wound around a cylindrical core 3. Good.

[0130] In addition to directly heating the fixing roller 1 as an object to be heated, as shown in FIG. 14, a core 3 in which a metal plate 1 is an object to be heated and a coil 2 is wound in the vicinity thereof is used.
May be provided. In this case, a metal heating plate 1, a coil 2 and a core 3 as shown in FIG. 14 may be disposed inside the fixing roller, or the metal plate 1 and the pressure roller 6 may be replaced with the fixing roller 1. The metal plate 1 and the pressure roller 6 are interposed via a flexible film that follows the movement of the recording paper.
And the like may be pressed against.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of one embodiment of induction heating of the present invention.

FIG. 2 shows that the input AC voltage (before rectification) of the DC power supply circuit 19 shown in FIG.
FIG. 6A is a voltage waveform showing an output voltage (after rectification) applied to a resonance circuit including a resonance circuit 10 and a resonance capacitor 10. FIG. 11A shows a case where the capacity of the smoothing capacitor 9 of the DC power supply circuit 19 is large, and FIG. Show the case.

3 is a waveform diagram showing a current flowing through a switch 17 shown in FIG. 1 by a solid line, an envelope level obtained by smoothing the current by a dashed line, and an output voltage of the DC power supply circuit 19 by a dashed line.

FIG. 4 shows the induction heating apparatus (the present invention) shown in FIG. 1 and FIG.
6 is a graph showing the frequency characteristics of the switch current of the conventional device (Comparative Example 1) shown in FIG.

FIG. 5 is a longitudinal sectional view showing an outline of a mechanism of a full-color copying machine equipped with the fixing device of the present invention.

6 is a block diagram showing a system configuration of an electric system of the full-color copying machine shown in FIG.

FIG. 7 is an enlarged sectional view of the fixing device 423 shown in FIG.

8A is a longitudinal sectional view of the fixing roller 1 shown in FIG. 7, and FIG. 8B is a transverse sectional view.

FIG. 9 is a block diagram illustrating a configuration of an electric system according to a first embodiment of the fixing device 423 illustrated in FIG. 7;

FIG. 10 shows the relationship between the material of the fixing roller 1 shown in FIG. 7, the current flowing through the switch 17 that energizes the electric coil 2 for heating the same, and the regenerative current flowing through the flywheel diode 28 connected in anti-parallel to the switch 17. FIG.

FIG. 11 is a graph showing changes in the switch current Sin and the regenerative current Sk depending on the roller material when the on / off duty of the switch 17 shown in FIG. 9 is increased at a constant speed.

FIG. 12 is a block diagram illustrating a configuration of an electric system according to a second embodiment of the fixing device 423 illustrated in FIG. 7;

FIG. 13 shows a fixing roller 1 of the fixing device 423 shown in FIG.
(A) is a longitudinal sectional view and (b) is a transverse sectional view.

14A and 14B show a modification in which the fixing roller 1 is a metal plate, wherein FIG. 14A is a longitudinal sectional view and FIG. 14B is a transverse sectional view.

FIG. 15 is a block diagram showing a configuration of a conventional type of induction heating device.

16 is a waveform diagram showing a current flowing through the switch 17 shown in FIG. 15 by a solid line, an average value thereof by an alternate long and short dash line, and an output voltage of the DC power supply circuit 19 by an alternate long and two short dashes line.

[Explanation of symbols]

 1: Heated object (heating object, fixing roller, metal plate) 2: Induction heating coil 3: Core 4: Thermal fuse 5: Separating claw 6: Pressure roller 7: Power supply 22: Smoothing choke coil 29, 30: Current Transformers 32, 33: voltage dividing resistors

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05B 6/14 H05B 6/14 (72) Inventor Masae Sakahara Shimei, Shibata-cho, Shibata-gun, Miyagi Prefecture 3-1 Within Tohoku Ricoh Co., Ltd. (72) Inventor Junichi Sasaki Nakamine, Shimada-cho, Shibata-gun, Miyagi Prefecture 3-1 Shinmei-do, Meiji-Do 3-1 Tohoku Ricoh Co., Ltd. F-term (reference) 2H033 AA02 AA32 BA25 BA30 BB18 BB28 BE06 CA07 CA23 CA30 CA45 CA47 3K059 AA04 AB19 AC03 AC07 AC33 AD03 BD21 BD24 CD09 CD10 CD39

Claims (7)

[Claims] 1. A resonance circuit including an electric coil disposed in the immediate vicinity of an object to be heated and a resonance capacitor connected to the electric coil,
In an induction heating method of chopping a direct current obtained by rectifying an alternating current by repeatedly turning on / off a switching element, a fluctuation of a voltage between the resonance circuit and the switching element is detected, and the switching element is turned on in synchronization therewith. ,
And detecting a current flowing through the switching element, and turning off the switching element after an on-time based on a time until the instantaneous value of an envelope level proportional to the voltage waveform obtained by rectifying the AC is reached. Characteristic induction heating method. 2. The induction heating method according to claim 1, wherein a temperature of the object to be heated is detected, and the on-time is adjusted so as to match a target value. 3. When a diode is connected to the switching element in anti-parallel, a regenerative current flowing through the diode is detected, and the electric current is detected based on a combination of a current flowing through the switching element and the regenerative current. 2. The induction heating method according to claim 1, wherein at least one of a material to be heated and a material to be heated is detected in the vicinity of the coil. 4. The induction heating method according to claim 3, wherein the on-time is adjusted according to a material to be heated. 5. A resonance circuit including an electric coil disposed in close proximity to an object to be heated to generate an induced current therein and generate heat, and a capacitor connected to the coil; and an alternating current for supplying power to the resonance circuit. A rectifying circuit for rectifying the rectifying circuit; an inverter circuit including a switching element for supplying a chopping current from the rectifying circuit to the resonance circuit and a diode connected in anti-parallel to the switching element; a driving unit for turning on / off the switching element; Voltage detecting means for detecting a voltage at a connection point between the electric coil and the switching element; means for detecting a current flowing through the switching element; and the driving in synchronization with resonance oscillation of the voltage detected by the voltage detecting means. The switching element is turned on through the means, and the current flowing through the switching element is a voltage wave obtained by rectifying the alternating current. Control means for turning off the switching element after an on-time based on the time to reach an instantaneous value of the envelope level proportional to the shape. 6. A cylindrical conductive roller for heating and pressing a recording medium on which a toner image has adhered; means for detecting the temperature of the conductive roller; A resonance circuit including an electric coil for generating a current to generate heat and a capacitor connected to the coil; a rectifier circuit for rectifying an alternating current to a direct current for supplying power to the resonance circuit; An inverter circuit including a switching element for energizing chopping current and a diode connected in anti-parallel to the switching element;
Drive means for turning on / off the switching element; voltage detection means for detecting a voltage at a connection point between the electric coil and the switching element; means for detecting a current flowing through the switching element; and detection by the voltage detection means. Time in which the switching element is turned on via the driving means in synchronization with the resonance oscillation of the applied voltage, until the current flowing through the switching element reaches the instantaneous value of the envelope level proportional to the voltage waveform obtained by rectifying the alternating current. Control means for turning off the switching element after a time obtained by adding a correction corresponding to a deviation of the temperature detected by the temperature detection means from a target temperature to the on time based on 7. A photoreceptor, means for charging the same, exposure means for irradiating a charged surface of the photoreceptor with light for representing an image, and developing means for visualizing an electrostatic latent image formed by the toner with toner 7. An image forming apparatus comprising: means for directly or indirectly transferring a visualized toner image to a recording medium via an intermediate transfer medium; and a fixing device according to claim 6, which heats and pressurizes the recording medium. apparatus.